An all too well known problem with any floating object, be it a buoy, vehicle, platform, or structure, is its tendency to pitch, heave, roll, and yaw in responce to the motion of the sea, such as waves and swells, which may or may not be induced by the wind. These motions are normally defined as follows: pitch is a fore-to-aft change in horizontal orientation of the body; heave is a total vertical displacement of the body; roll is a side-to-side change in horizonatal orientation; and yaw is the horizontal azimuthal side-to-side rotation of the vehicle. Unfortunately all these motions of a buoyant platform are combined into a complex motion having the elements of all four distinct motions, and obviously it would be desirable to eliminated them all.
When the wave system, giving rise to the motions on the platform, are wind induced, the wave length can be determined by known methods such as accelerometers and other measuring devices (see for example, U.S. Pat. No. 3,800,601 to the inventor, disclosing a theory of wind-maintained seas and methods of measuring same). The fact that a wave system is generally predictable, permits detection of the wave length and then compensation for the motion created on a buoyant platform, vessel, or the like. It is not practical to compensate for wave patterns that are not predictable in wavelength, such as are developed from unknown distant disturbances.
It is desirable to stabilize a floating platform for many reasons and applications, such as for off-shore oil drilling, in oceanography as for taking bottom samples, ocean floor surveying, and recovering objects from the ocean floor. Other recent military considerations for the use of floating platforms are floating islands and landing fields or runways with their necessary ancillary facilities and equipment.
The prior art shows floating islands or sea platforms that may or may not be stabilized, and of course, many that are secured to the ocean floor. The stabilized platforms of the prior art involve the use of elements, buoyant or otherwise, capable of deforming vertically to absorb the rise and fall of the waves under the platform. These devices suffer from the disadvantage that they only attenuate the response of the platform to the wave disturbances. They do not decouple the disturbance so as to remove it.